Rayleigh--Taylor instability in a viscoelastic binary fluid

TL;DR

This paper investigates how polymer additives influence Rayleigh--Taylor instability in immiscible fluids, revealing that elasticity accelerates the instability growth rate, with analytical and numerical methods supporting these findings.

Contribution

The study introduces an analytical and numerical analysis of RT instability in viscoelastic fluids using the Oldroyd-B model and phase-field approach.

Findings

Elasticity increases the growth rate of RT instability

Analytical results align with numerical simulations

Growth rate remains slower than in pure solvent

Abstract

The effects of polymer additives on Rayleigh--Taylor (RT) instability of immiscible fluids is investigated using the Oldroyd-B viscoelastic model. Analytic results obtained exploiting the phase-field approach show that in polymer solution the growth rate of the instability speeds up with elasticity (but remains slower than in the pure solvent case). Numerical simulations of the viscoelastic binary fluid model confirm this picture.